Agile Web Development with Rails 3.2

Agile Web Development with Rails 3.2

If we add two products to cart, then we create a row for table “cart” and two row for table “line_items”.
What happens if now we close our Web Explorer? happens that never is deleted this row for table “cart” and the two rows for table “line_items” .
If many people do this, our data base will be full with trash in tables “cart” and “line_items” .
This is not a problem if we complete a order because we can delete this order.